Special Feature | Audio Video Bridging
UNDERSTANDING AUDIO VIDEO BRIDGING
Henning Kaltheuner | Riedel
A new emerging standard offers a single network to support the transport of all data and signals.
Henning Kaltheuner, Head of Product Management, Riedel
For many people, Ethernet-based data transport is still associated with the uses found in current network applications such as media servers or data transport. But Henning Kaltheuner, head of product management for Riedel examines how the standards underlying Ethernet protocols offer more versatile possibilities than at first meet the eye.
The idea of transporting audio or connecting intercom panels over an Ethernet-based LAN network has been the dream of many system planners. Yet, up to now, IP-intrinsic problems such as latency, poor reliability and synchronization issues have stood in the way. Now, with the appearance of the AVB standard, this dream will become a reality.
AVB, Audio Video Bridging, is a new IEEE Ethernet standard. In general, the IEEE 802.1 AVB standard regulates the basic parameters for a series of protocols that enable the real-time transport of media data through Ethernet networks. In this way, the AVB standard allows for the simultaneous transport of different protocols and the execution of parallel applications within a network in real time so that data from computers can run over the same infrastructure as the intercom installation or the audio distribution network.
Taking advantage of the AVB standard, theaters now need only to install a single network to support the transport of all data and signals. This approach drastically reduces installation costs and maintenance while increasing the network’s flexibility. Expanding the system or adding to the number of users no longer means that new cables inevitably will need to be pulled; additional user stations and
44 | May/June 2013 |
ibeconnects.com
other equipment can simply be connected to the existing Ethernet infrastructure.
AVB Basics
The Ethernet protocols from IT applications present a fundamental problem in that transporting high-quality media data, such as audio and video signals, without latency over local area network (LAN) infrastructures is impossible. One issue is that other data and protocols are being transported over the same network. The inability of conventional Ethernet applications to prioritize the transport of particular data dependably leads to problems with the transport itself. Furthermore, the synchronization mechanisms currently used in Ethernet networks do not meet the needs of high- quality data transport and therefore make real-time audio and video signal transport impossible.
This is where AVB changes the game. AVB is a bundle of standards that enable the real-time transport of audio, video and data within an Ethernet network.
If system planners are to take advantage of AVB with success, they must understand two important conditions for implementation. The first of these conditions is that AVB only works on a local network. Connections over wireless LANs or wide area networks (WANs) are not yet possible. The second of these conditions is that AVB can run only in combination with switches that have been set up and are compliant with the AVB protocol. This means that the hardware must include a special chipset if it is to be operational. Switches that are not AVB-compatible can be used further down the network, but AVB
Next to crucial cost savings, especially with respect to installation costs, AVB offers exciting new possibilities.
data will not be available past this point. (Other data, however, still will be able to pass across the network.)
What this means for theaters and other facilities is that they can selectively expand their existing networks to create an AVB network without introducing any problems with existing data transport. Even if there is no immediate need for extended network capabilities, system planners can design new installations with an AVB- compatible infrastructure in mind, thus allowing AVB networks to be implemented smoothly at a later date.
The adoption of AVB sounds much more complicated than it actually is. In fact, AVB- compatible installations are made straightforward by a growing range of AVB-compatible hardware already offered by well-known manufacturers. Apple, Intel, and Cisco are just a few of the prominent names among the large number of companies supporting
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